'93 240 failed emission test in Ontario

Got 83 on HC (limit is 66), got .40 on CO (limit is .37) and got 903
on NO (limit is 505).

Plugs were changed, air filter was changed and oil (Mobil 1) was
changed prior to test. I checked the thermostat in the air box and is
working fine.

Car is ONLY driven in city and has 167,000KM (~ 100,000 miles).

Do you have any suggestions? I've been thinking about replacing the
catalytic converter with originalVolvo part.

Thanks.

 

First I would check all of the ignition components. Assuming that is
all well, I would put in a new oxygen sensor using a direct fit type,
not the universal sensors which require splicing wires. Bosch and other
suppliers offer direct plug in replacements. If you 240 still has it's
factory sensor there is a good chance that it is responding poorly.

Before replacing the cat I would get a before and after emissions probe
done. That will tell the story on cat. effectiveness.

Volvo original cats are very expensive. I replaced the one on our '93
with a Bosal aftermarket unit at a fraction of the cost of a Volvo unit
with good results and it has passed California smog testing.

 

I forgot to write that such high readings only happen during driving
test. At idle, I'm passing with flying colors! At idle, HC is 45
(limit is 200) and the CO is 0.02 (limit is 1.00).

thanks

 

It should run cleaner than that even with no cat at all, something is wrong.
If it's only been driven around town, it may have buildup on the valves,
could also be dirty injectors. Try dumping a bottle of Techron in the tank,
then take it out on the highway and thrash it a bit to burn out carbon
deposits.

 

I'll do the Techron, but would you also recommend changing the cat?
Volvo dealer told me last week that it was $383 (CAD) + tax for the
part. I'll do it myself.

Thanks for the reply.

 

The cat in my mom's 240 crumbled internally years ago and has been hollow
ever since, it still passes the emissions test easily. Unless the cat is
plugged or crumbled, there's no sense in replacing it.

 

My concern is that the high emissions are across the board. Normally the
things that make CO go up make NOx go down and so on.

My knowledge and experience are not enough to base a decision on.

Mike

 

That is why I suspect the Oxygen sensor being slow to respond. It can
give you rapidly alternating rich and lean conditions which makes all
the numbers go up. The emissions sniffer does an averaging function.

John

 

I hadn't thought of that. Some O2 sensors can get mighty bad without the
"check engine" light coming on. I think Volvos are among the least critical
of O2 function. At any rate, the sensor is undoubtedly a ripe old age by now
if it is the original and replacement would be a good start. Bosch
replacements have a bad reputation; OEM through a discount reseller would be
a safer choice.

Mike

 

The OEM sensor *is* Bosch, I hadn't heard of the bad reputation, can you
elaborate more on that?

 

No direct experience myself, but a few of the experienced regulars in the
alt.autos.honda forum warn against Bosch O2 sensors (the universal
replacements). The response speed initially is supposed to be substandard
and the useful life barely two years (according to one source.) The same
source is also a proponent of replacing O2 sensors every ten years,
especially if throttle responsiveness or fuel economy is dropping off. I
have no opinion yet, but I'm keeping my eyes open.

Aftermarket parts and fluids is a touchy matter among Honda/Acura folks.
Power steering fluid and transmission fluid (manual and automatic) are
proprietary to Honda; use of the wrong PS fluid destroys the PS seals
quickly. Aftermarket ignition parts as well as starters and alternators are
often so flimsy compared to OEM that many Honda die-hards accept nothing
else. (I've experienced bad aftermarket ignition parts myself.)

Mike

 

Thanks to all for the replies. I'll keep you up to date, but it will
take some time. I went to Canadian Tire and bought a bootle to clean
the injectors. After I empty the gas tank, I'll do another treatment,
this time with a liquid supposed to clean injectors, valves, etc.

After I'm done, I'll try the test again and will come back to provide
you the results. But I must use two gas tanks... Give me ~ 2-3
weeks...

 

Be sure to run a tank through it after you use the treatment. That stuff
will skew the results (meaning fail it) for sure.
And, (in case you didn't know) you will get best results from the
cleaner if you do many stops and starts rather than one 400 mile road trip.
It seems the thermal cycles when the motor heats up and cools helps
break loose the crud.

 

Didn't know that. Thanks for the tip.

 

I've installed Bosch replacement O2 sensors on several cars with no
issues. The big deal is to make sure and get a direct fit one, not the
"universal" splice in variety.

NGK and NTK sensors are also good brands. Volvo originals are
generally high priced.

John

 

Sounds good to me.

Mike

 

Where can one get NGK O2 sensor? Muffler shops?

Thanks.